In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have lead to rapid progress in the field of miniaturization. Typically, these miniaturization techniques involve shortening the wavelength of the exposure light source. Conventionally, ultra violet radiation typified by g-line and i-line radiation has been used, but nowadays KrF excimer lasers (248 nm) are the main light source used in mass production, and ArF excimer lasers (193 nm) are now also starting to be introduced in mass production. Furthermore, research is also being conducted into lithography techniques that use F2 excimer lasers (157 nm), EUV (extreme ultra violet radiation), and EB (electron beams) and the like as the light source (radiation source).
Resists for use with these types of short wavelength light sources require a high resolution capable of reproducing patterns of minute dimensions, and a high level of sensitivity relative to these types of short wavelength light sources. One example of a known resist that satisfies these conditions is a chemically amplified resist, which includes a base resin and an acid generator that generates acid upon exposure (for example, see patent reference 1). These chemically amplified resists include positive resists in which the alkali solubility of the exposed portions increases, and negative resists in which the alkali solubility of the exposed portions decreases.
These types of resists require favorable lithography characteristics (including resolution, depth of focus characteristics, and resist pattern shape and the like).
Moreover in recent years, as the demands for higher resolution resist patterns have increased, in addition to the characteristics described above, an improvement in the level of defects (surface defects) within the developed resist pattern is also required. These defects refer to general abnormalities detected by inspection of the resist pattern following developing, from directly above the resist pattern, using a surface defect inspection device such as that manufactured by KLA Tencor Corporation (brand name: KLA). Examples of these abnormalities include post-developing scum, foam, dust, bridges across different portions of the resist pattern, color irregularities, and precipitated deposits. Particularly in the case of formation of very fine resist patterns of 130 nm or smaller using an ArF excimer laser or more recent light source, namely an ArF excimer laser, a F2 excimer laser, EUV or EB or the like, the problems associated with resolving these defects have become even more demanding.
[Patent Reference 1]
Japanese Unexamined Patent Application, First Publication No. 2003-167347